There is a third location for a NAND FLash, so you may be able to add more and/or replace the existing chips.

I would not try that until I was able to build ubuntu from scratch for it, so the flash drivers could be reconfigured.

I did see one thread someplace where someone used the 16GB SDHC card slot to mount the /home partitionand by doing this all the really active writing occurred on the removable memory because once the on board NAND Flashstarts to get failures it will need to be replaced.